Master clock



Sept. 20, 1932 c. E LARRABEE 1,378,931

MASTER CLOCK rma Aprn 2s, leso s Sheets-snm 1 v Hal.

20, 3932- c. E. LARRABEE v 1,878,931

ASTER CLOCK 'und April 26. 1930 :s sheets-snee: 2

Patented Sept. l20, v1932 UNITED s'raras PATE-NT OFFICE' CLINTON E. LABRABEE, F BINGHAMTON, NEW YORK, ASSIGNOB '10 INTERNATIONAL TIME RECORDING COMPANY OF NEW YORK,

OF NEW YORK OF NEW YORK, N. Y.,'A. CORPORATION MASTER CLOCK application mea Aprn 2a, 1930. serial No. 447,611.

v The present invention relates to clock systems in general and particularly to improve` ments in the construction of master clocks commonly used in connection with vsystems 5 wherein the secondary clocks are automatically synchronized with the master clock at regular intervals of time.

It has been the practice heretofore to equip master clocks lwith certain contacts co- 10. operating with the clock movements whereby impulses of electric current are transmitted to the secondary clocks at regular periods of time for the purpose of driving the secondary clocks and also at predetermined intervals of time for effecting synchronization of any of the secondary clocks which may spect to the master clock. Such synchronizing and impulse contacts are commonly actuated by cams driven by the earin of the clock train of the master cloi andg usually include a rapid impulse contact which heretofore Ahas been directly actuated by means mounted upon the verge staif of the escapement mechanism.

The cam actuated contacts have usuall consisted of a pair of contacts each of whic was borne by and insulated from an arm actuated by a separate cam,

adapted to cooperate to produce a rapi closure and interruption in the circuit. The contacts themselves, being movable, were connected by means of a spirally arranged length of wire to a fixed binding post or contact stud in order to provide for the pas-- sage of current through the contacts to the clock circuits and at the same time rmit the contacts to be operatively control ed by their respective cams.

40 The rapid impulse contact commonly consists of a contact member carried by the verge staff and adapted to make contact with astationary Contact carried by the main frame of the clock once each time the verge staif p ,45 oscillates under the influence of the pendulum.

Letters Patent No. 1,687,491, granted .c Octobery 16, 1928 to James W. Bryce, illustrates a master clock including contacts of the 5 type described above, the minute impulse conagainst the periphery of the'cam in order to be fast or slow with re' both cams being n tacts and certain of the synchronizing ycontacts being cam actuated while the rapid impulse contacts are actuated by the verge staff in the manner mentioned.

It has been found in practice that the types of contact illustrated in the patent men-v tioned have certain defects in practice whichy interfere with the proper action of the master clock. The flexible coiled conductor; wire comprising the electrical connection between the cam operated contacts and the binding posts or Contact studs causes trouble owing to the fact that a very light s ring .tension must be used to hold the camV ollower arms reduce the friction load on the clock train to a minimum. It has been found that the usual flexible coil of conductor wire is apt to exert a spring effect upon the cam follower arms in:` addition to the sprin s holding the cam follower arms against t e cams with the result that the action of the contacts is uncertain since the follower arm springs may be either' completely neutralized or augmented in tension. The former condition may render the contacts inoperative while the latter condition increases the friction load on the clock train and has an adverse effect on the accuracyof the clock.

When the contact operated by the oscillation of the verge staif'is of the type shown in the above patent there is a tendency to retard the pendulum of the clock and shorten its swing in one direction thereby adversely effecting the accuracy of the clock. The spring tension in the contact linger carried by the verge is extremely diilcult to adjust satisfactorily and furthermore fatigue tends to cause the spring rtension to vary so that thev contacts tend to get out of adjustment after a time. The gradual weakening of the spring contact carried by the verge tends to make the swing of the pendulum greater on one side astime goes on thereby effecting the accuracy of the cloc l It is the primary object of the present invention to improve the construction and arrangement of the variouscontacts involved in the construction of a masterpclock thereby intacts being shownin closed position.

creasing the reliability of the contacts and eliminating the defects already pointed out.

Other objects and advantages of the present invention will be pointed out in greater detail in the accompanying specification and claims and shown in the drawings, which, by way of illustration, show what, for the present at least, may be considered a preferred embodiment of the invention.

In said drawings:

Fig. 1 is a vertical elevation of a master clock illustrating the construction and arrangement of the various contacts, the rapid impulse contacts and the thirty-second contacts being shown in open position.

F ig. 2 is a view similar to Fig. 1, the rapid impulse contacts and the thirty-second con Fig. 3 is a view of the thirty-second and fifty-minute contacts and their actuating mechanism, both contacts being open;

Fig. el is a top plan view illustrating the construction and arrangement of the rapid impulse contacts;

Fig. 5 is a circuit diagram showing a self synchronizing clock system controlled by a master clock embodying the present invention.

Fig. 1 illustrates the general arrangement of a master clock. Since the clock itself is of a well known construction, it will not be described in great detail herein. The numeral 10 represents the usual verge staf which is oscillated by the pendulum 11 of the clock. The verge statt is given one complete oscillation in two seconds thereby controlling the escapement wheel so as to produce one complete revolution of the escapement wheel in one minute. The pendulum 11 as customary is supported by a post- 12 and is coupled to the verge stati by a member 13 to which the verge is adjustably connected. The usual screws 14 provide for the adjustment of the verge 15 in a well known manner. The plates 16 further provide for adjustably raising or lowering the verge staff.

rlhe master clock is provided with rapid impulse contacts 17 which are normally open but are adapted to be closed once every two seconds in the present instance through the medium of mechanism now to be described in detail. The rapid impulse contacts 17 are actuated in a novel manner by means carried by the verge stati 10 comprising a member 18 which is firmly fastened tothe verge stall' by means of clamping blocks 19 and screws 20. A weight 21 carried by the right end, Figs. 1, 2 and 4, of the member 18 acts as a counterbalance for a similar weight 22 carried by a. member 23 pivoted at 24, upon the member 18.

The member 23 may be adjusted relative to the member 18 by means of a screw 25 provided with a suitable locknut and is provided with an extension 26 bearing an insulation disc 27 adapted to bear at times upon the upper contact spring of the contacts 17.

It will be clear from the foregoing descri tion that the Swingin of the pendulum oft e clock will oscillate t e verge staff and consequently the member 18 so as to alternately raise and lower the weighted member 23 thereby actuating the contacts 17. The weight 22 is just heavy enough to close the contacts 17 whenever the endulum swin far enough to the right, ig. 2, to permitthe' insulated disc 27 to come into contact with the upper contact spring of the contacts 17. B Avarying the adjustment ofl the screw 25 t e time at which closure of the contacts 17. is eflected may be readily adjusted. It will be clearly seen that the closure of the contacts 17 is edected solely by the weight of member 23 and therefore the pendulum is relieved of the work of closing the contacts. It will be obvious that the inertia of the weight 22 and member 23 will prevent the upper contact spring of contacts 17 from reversing the motion of the member 18 too rapidly thereby eliminating the kick which result-s when one of the contacts 17 is carried by the verge staff as was formerly the case. Furthermore, the screw 25 makes it ossible to readily adjust the time of closure ci) the contacts so that the slight unbalancing of the member 18 and the verge staff near the end of the swing of the pendulum is reduced to a minimum thereby increasing the accuracy of the clock.

It is true that the pendulum will be efected slightly when the weighted arm 23 is arrested by the closing of the contacts; however, the effect on the pendulum will be constant since the weight of said arm is constant and always takes effect at the same point in the swing of the pendulum. By making the upper contact member of contacts 17 of a very weak spring having just sutlicient resiliency to open said contacts, the effect or said spring contact member on the accuracy of the clock may be made constant and so slight as to be scarcely noticeable even over a long period of time. vWhile the pendulum is slightly retarded by the relative lifting of the greater part ofthe weight of arm 23 from member 18, the effect is to shorten by a small amount the distance traveled by the pendulum to the right Fig. 1) and lengthen its swing to the left by the same amount.

It will be clear that the whole elfect will be to cause the pendulum to swing slightly off the center of gravity of the pendulum system without actually affecting its regularity by increasing or decreasing its period of oscillation. By suitable adjustment of the verge in a well known manner the slight angular displacement of the path of movement of the pendulum may be fully compensated. It will be obvious that the only duty required of the pendulum is to swing regularly and this result is secured in the present arrangement although the pendulum may -not swing ,equal distances from a vertical axis through the center of gravity of the system.

. The resiliency of the spring contact members carrying contacts 17 .will vary as time goes on, however, this variation will be slight since said contacts have little work to do and the upper one may be very weak, so that once adjusted, the mechanism will function over a long period of time without noticeably affecting the accuracy of the clock.

The minute impulse contacts 28 are nor-4 v underlying the lower member of the spring contacts 28.

on the peripheryv of the cam 29 and is held in contact therewith by a spring 37 which is tensioned between ,afixed stud and the third arm of the member 33. It will be clear that the spring 37 also -h'olds the member. 32 in contact with the cam 29. The arm 36 is of lsuilicient length to permit it to drop off the high points on the cam 29 a few seconds before the follower 32 drops off the high points and for this reason the follower 32 extends slightly farther to the right, Fig. 1, than the arm 36. When the follower 32 and the arm 36 both rest upon either of the high points of the cam 29 the contacts 28 will be open as illustrated in Fig. 2. The' same will be true when both rest upon a low point in the cam.

'In order to effect closure of the contacts 28 it is necessary that the arm 36 move downwardly relative to the follower 32. This relative movement is accomplished in the following manner: As the 'cam 29 revolves in a clockwise direction the follower 32 and arm 36 will be gradually raised until eventually the arm 36 will drop olf the high point in the cam' before the follower 32 drops off the high point. The tension of the spring 37 will now cause the three armed member to rock clockwise to the position shown in Fig. 1

' thereby veffecting closure of the contacts 28.

A few seconds later the follower 32 will drop off the high point in the cam 29 with the result that both the members 32 and 33 will be pulled down by the spring thereby opening the contacts 28. A

The contacts 38 and 39 are actuated by a pair of cams 40,-41 carriedby the minute larbor 42 which makes one complete revolution per hour.` yCo-operating with the cam 41 is a cam follower 4 3 substantially similar in construction to thel follower 32. A three arm lever 44 similar to the three arm mem- An arm 36 is adapted to bear ber 33 is pivoted upon the follower 43 and has an arm bearing on the periphery of the cam 40. Another of the arms of the' three arm member '44 carries an insulating .disc 45 which bears on the underside of the lower of the two central spring contact members of contacts 38, 39. The two central mem- It is necessary that the lever 44be actuated by the cams 40, 41 in such a manner that either the upper contact-38 or the lower contact 39 may be held closedJor both held open and to accomplish'that result the cam 40 is.

provided with two steps of different heights while tlre cam'41 is provided with only one` step. AThen the follower 43 andthe arm 47 rest on the highest points in their cams 40, 41 the contacts 39 are closed which is also the case when both rest on the lowest points in the cams, the position of the parts for the latter situation being illustrated in Fig. 1. The upper contacts 38 are closed when the follower 43 is onthehighest point in cam 41 while the arm 47 is on the lowest point in cam 40 as shown in Fig. 2. Neither of the contacts 38, 39 are closed when the follower 43 is'on the high point of cam 41 and the arm 47 is resting upon the intermediate step in cam 40, as shown in Fig. 3.

. The cam 40 is timed so that the arm 47 drops from the high point 48 in the cam to the intermediate step at about 49 minutes and 30 seconds after the even houriwhile the intermediate point 49 is positioned to permit the arm 47 to drop still further at about 59 minutes and thirty seconds after the hour. The high point in cam 41 is timed. to become effective to release the follower 43 just before theminute impulse contact 28 closes for the point 48 on cam 40 to the intermediate step under the infiuence ofspring 46 which rocks the lever 44 clockwise relative to follower 43 thereby opening contacts 39. Both of the contacts 38, 39 remain open until about 30 seconds after the 59th minute when the arm 47 vdrops from the intermediate point 49 to the lowest point in cam 40 thereby permitting t0 the C be connected to the the spring 46 to further rock the lever 44 clockwise relative to follower 43 and causing the closure of contacts 38. The contacts 38 remain closed until just before the cam 29 permits contacts 28 to close for the 60th minute impulse prior to which the follower 43 will drop off the high point in cam 41 and again close contacts 39.

Fig. 5 illustrates a circuit diagram which explains the function of thevarious contacts just described. The principle of operation is substantially the same as'in the patent to Bryce hereinbefore mentioned, certain parts having been eliminated. Only a brief description of the system will be given herein since the system itself forms no part of the present invention.

The letters A, B and C represent the three well known circuit wires of a system to which thesecondary clocks 50, 51 are connected as in the patent to Bryce already mentioned. Each secondary clock is provided with a cam 53 adapted to close onel or the other of contacts 54, 55. The driving magnet 56 of each secondary clock is connected wire and also to the central common contact member Vof the contacts 54, 55. The cams'53 are proportioned so that contacts 54 are opened and contacts 55 arel closed during a period of time from about 30 seconds of the hour to about 14 minutes and thirty seconds after the hour. At all other times contacts 54 are closed. The function ofthe cams 53 and contacts 54, 55 is to transfer the circuit through nthe drivingmagnet 56 from the A wire to the B wire during the synchronization period. Thel C wire may be considered as an extension of one of theline wires 57 58 supplying the system with electrical current.

The master clock is provided with a winding magnet 59 adapted to wind up the power spring 60 peri0dically, in the present case once each minute, the magnet being connected between the A and C wires. The double pole switch 61 is normallythrown to the left, Fig. 5 so as to connect the minute impulse contacts 28 across the line wires 57, 58 in series with the'master relay 62. Each time the master relay 62 is .actuated by the closure of contacts 28y the contacts 63 ofthe master relay conneet'the A wire with line wire 58 thereby delivering an electrical impulseto the driving magnets 56 and advancing the secondary clocks one minute and at the same time energizing'winding magnet 59. As long as contacts 39 are closed the impulses may travel over either the A or the B wires but during the time the contacts 39 are open theA B wire is disconnected and any of the secondary clocks which may B wire will not receive an impulse and will stop until the contacts 39 are again closed after the synchronization period is complete.

If clocks 50 and 51 are both on time with the master clock they will be both transferred to the B wire simultaneously about thirty seconds before the hour and, since contacts 39 close a few seconds prior tothe closing of contacts 28 bot-h 0f the secondary clocks will receive the 60th'impulse simultaneously.

lIf clock 50 is on time and clock 51 fast by, say ten minutes, clock 50 will continue to receive the minute impulses over the C wire while the clock 51 will reach the 59th minute first-and will stop until the contacts 39 are reclosed whiclrwill not take place until clock 50 receives the 60th impulse just after contacts 39 are closed by the master clock,'the 60th. impulse being returned over the B wire. All secondary clocks which are on time reina-in connected to the B wire for a. period .of fifteen minutes before the cams 53 connect the A wire` to the clocks.

If the clock 51 happens to be slow by, say ten minutes, it will be ten minutes behind the other clocks when they receive the 59th impulse and will still be vconnected to the A wire after all of the other clocks have been transferred to the dead B wire. As stated hereinbefore contacts 38 are closed for about 30 seconds between the 59th and 60th impulses thereby connecting the relay G2 in series with the rapidv impulse contacts 17 across the line wires 57, 58. The result is that a rapid succession of impulses will be delivered to the clcck 51 which is slow and still connected to the A wire. The rapid succession of .impulses sent over the wire advances the minutes hand of clock 51 until the operation of its cam 53 automatically transfers the clock 51 to the dead B Wire which will occur when the 'clock 51 reaches thev 59th minute. All of the clocks have now been transferred to the B wire so that when the 60th minute impulse is sent over the C wire all of the clocks will be advanced to the hour position and will be in synchronism. i

The double pole switch is provided for the purpose of connecting the rapid impulse contact 17 directly in series withthe relay 62 when it is desired to advance all clocks simultaneously one hour when correcting the system to'daylight saving time or when the clocks have been stopped .by an interruption in the power supply for a longer period of time than can be taken care of by the synehronization period. The entire system-can be entirely'di'seonnected by means of switch 61 when it is necessary to turn the clocks 'back an hour at the end of the daylight saving p eriod. Y

`l't'is thought thatthe foregoing explanation will clearly explain the function and mode of operation of the various contacts and for present purposes may be considered suiiicient. f

The principal advantages of the improved contacts is the greater reliability and eiiiciency obtained through the more positive action. The reduction in the friction load on the clock trainand the elimination of the uncertainty of operation of the contacts which was formerly sults in an improved operation of the system as a Whole and an increase in the accuracy ot the master clock. The adjustable feature of the rapid impulse contacts is al very decided yadvantage brought about by the present construction.

The'present invention, for sake of convenience in description and to assist in a clear understanding of the principles involved, has been shown as embodied in the purpose of actuating certain specilic contacts, however, it is not desired to limit the invention to the precise embodiment shown and described as it is capable of modification and adaptation to other types of clocks or apparatus as Well, all such modiications and adaptation falling within the scope of the claims Which follow.

I claim:

1. In a circuit controllin device, a frame, contacts mounted in said Irame, a member pivotally mounted in said frame adjacent for periodically said contacts, an arm mounted on said member intermediate the ends of the latter and adapted to operate said contacts by a pivotal movement relative to said member, means ment of the arm to operate said contacts and thereafter a second pivotal movement of said member to restore said contacts to their former condition, and means connected to said arm for effecting both pivotal movements of said arm and member under control of the first named means.

2. In combination with a master clock, a

frame, a pair of normally open spring cony tacts ixedly mounted in the frame, a. member rockably mounted in the Jframe and having pivoted intermediate its ends a rock arm provided with an extension adapted to close said contacts When the arm is rocked relative to said member, a cam driven by the master clock for permitting periodical rocking of said arm to close said contacts, a second cam movable with the first cam forpermitting a rocking movement of said member to open said contacts, and means connected to said arm for effecting both rocking of said arm and said member to first close and then open said contacts under control of said cams.

3. In a circuit closing device, a frame, a pair of spring -contact members ixedly mounted in said frame and adapted to be n found in practice re permitting pivotal move-4 nature. l

CLINTON E. LARRABEE.

a master clock for l 

